Increasing concerns with the effects of Freon and other refrigerant gases on the ozone layer of the atmosphere have led to the adoption of regulations controlling the discharge and use of refrigerant gases. Regulations have been promulgated for the automotive industry in the United States requiring new automobiles manufactured in the years to come to employ "ozone-friendly" refrigerants which do not damage the earth's protective ozone layer.
Nevertheless, there are literally millions of automobiles currently in use, and to be manufactured before the new emission regulations come into effect, having air-conditioning systems which employ Freon or other refrigerant gases which are harmful to the ozone layer. It is contemplated that vehicles whose air-conditioning systems are compatible with the new, ozone-friendly refrigerants may be recharged with such new refrigerants during periodic maintenance, but in order to insure that harmful refrigerants are not employed, recharging fittings associated with older automotive air-conditioning systems will not be compatible with the charging equipment employed with new refrigerants.
Accordingly, a need exists for a method to charge the air-conditioning systems of automobiles currently in use with new, ozone-friendly refrigerant through a means other than their existing charging fittings. One proposal has been to employ valve assemblies capable of clamping onto the refrigerant line of essentially any automotive air-conditioning system, piercing that line to provide access to its interior, and then introducing the new ozone-friendly refrigerant therethrough. Line piercing valves of this general type are disclosed, for example, in U.S. Pat. No. 4,611,624 to Snyder, owned by the assignee of this invention. The '624 Snyder patent discloses a valve assembly having housing elements which clamp onto a section of tubing, one of which is formed with a projection having an internal bore carrying a one-way valve including a piercing pin at its lowermost end. Structure is provided to axially move the one-way valve within the projection of the clamping element so that its piercing pin punctures the tubing to provide access to the tubing interior. Material such as refrigerant can then be introduced through the one-way valve into the tubing.
One limitation of valve assemblies of the type disclosed in the '624 patent is that difficulties arise in the event of failure of the one-way valve. Because the one-way valve in the '624 Snyder patent is permanently mounted within one of the clamping elements, a failure of such one-way valve requires replacement of the entire valve assembly. A problem then arises in obtaining a good seal at the point where the line was initially punctured. It is exceedingly difficult to place the clamping elements of a new valve assembly in the exact position as the previous valve assembly so that the puncture in the tubing can be sealed when the air-conditioning system is recharged. As a result, the tube itself will often need to be replaced leading to additional expense, particularly involving labor costs of the mechanic working on the system.